Atrioventricular block after fingolimod resumption: a consequence of sphingosine-1-phosphate axis alteration due to COVID-19?

During the COVID-19 pandemic, concerns raised regarding the use of immunosuppressants in multiple sclerosis, even if current data do not support an increased risk of infection. Although fingolimod can be temporarily suspended during COVID-19, the benefit-risk balance of suspension can be challenging. Till now, no adverse events have been described after the resumption of fingolimod, following a previous discontinuation. We report the occurrence of atrioventricular block following fingolimod restart. Fingolimod acts on sphingosine-1-phosphate-axis, a pathway that is altered with COVID-19 and hypoxic conditions. Herein we discuss how these metabolic changes may have influenced fingolimod pharmacology leading to a cardiac event.